An electronic wagering gaming machine system includes a display, one or more input controls, one or more ultrasound emitters and a sensor that detects the location of a person in proximity to the display. Control circuitry executes wagering game software that receives input commands entered via the input control(s), to display graphics output from the wagering game software responsive to the input commands, and to generate public and private sound signals in an audible frequency range. The private sound signals may be directed to the detected person's location by modulating one or more ultrasound carrier waves with the private sound signals and outputting the modulated ultrasound waves toward the detected person's location via the ultrasound emitter(s). The public sound signals may be played in the audible frequency range via the audio speaker(s).